EXPRESSION OF THE MURINE PROSTAGLANDIN (PGH) SYNTHASE-1 AND PGH SYNTHASE-2 ISOZYMES IN COS-1 CELLS

Plasmid vectors were constructed which allowed expression of the mouse prostaglandin endoperoxide (PGH) synthase-1 and PGH synthase-2 isozym es in cos-1 cells. Efficient expression of the PGHS-2 isozyme required the truncation of the entire 3'-untranslated region of the PGHS-2 cDN A, possibly due to the presence of multiple AUUUA sequences which may destabilize the PGHS-2 mRNA. The length of the 3'-untranslated regions of the murine and ovine PGHS-1 isozymes, which do not contain AUUUA s equences, did not affect the efficiency of expression of these protein s. The murine PGHS-2 isozyme catalyzes the same cyclooxygenase and hyd roperoxidase activities as the ovine and murine PGHS-1 isozymes. The m aximal activities of the mouse enzymes expressed in cos-1 cells was ab out equal, but both were only about a third that seen with the sheep e nzyme. Whether this reflects differences in the turnover rate of the m ouse and sheep enzymes, or differences in the efficiency of expression in cos-1 cells is not known.